In magnetic storage devices such as hard disk drives (HDD), read and write heads are used to magnetically read and write information to and from storage media. In a HDD, data may be stored on one or more disks in a series of adjacent concentric circles which may be referred to as data tracks. A HDD may include a rotary actuator, a suspension mounted on an arm of the rotary actuator, and a slider bonded to the suspension to form a head gimbal assembly (HGA). In a traditional HDD, the slider carries a write head and read head, and radially slides over the surface of the storage media, e.g., a disk, under the control of a servo control system that selectively positions a head over a specific track of the disk. In this one read head (reader) configuration, the reader is aligned over the center of a track for data read back.
As HDD storage capacities have increased, the data track separation has decreased and the density has increased. Increasing magnetic recording density entails narrower-track widths and narrower shield-to-shield (S-S) spacing on the read heads. Current tunnel magnetoresistance (TMR) read heads can include among other elements, a pinned layer coupled to an antiferromagnet (AFM) layer. The TMR read heads may further comprise a free layer separated from the pinned layer by a barrier layer. In current perpendicular magnetic recording (PMR) read heads, little room exists, if any, to further reduce S-S spacing due to the existence of the AFM pinning material underneath the pinned layer. Attempts to narrow the S-S spacing by removing the AFM layer have been unsuccessful because AFM-free TMR read heads are prevalently magnetically bi-directional.